Problem P. 4099. (October 2008)
P. 4099. A sample of water of mass m_{1} and of temperature t_{1} is in a thermos flask, and warmer water of mass m_{2} and of temperature t_{2} is poured to it. After the themal equilibrium is reached the temperature is measured. Next time, because we are curious, we swop the two samples of water, so the colder water of mass m_{1} and of temperature t_{1} is poured into the thermos in which there is the other sample of water of mass m_{2} and of temperature t_{2}. Surprisingly it is found that the equilibrium temperature in the second case is different from the one measured in the first time.
a) How can you explain this difference?
b) The difference between the two equilibrium temperatures is 1.9 ^{o}C. What can you deduce from this?
Data: m_{1}=300 g, t_{1}=20 ^{o}C, m_{2}=600 g, t_{2}=80 ^{o}C.
(4 pont)
Deadline expired on 11 November 2008.
Statistics:
>118 students sent a solution.  
4 points:  80 students. 
3 points:  15 students. 
2 points:  15 students. 
1 point:  4 students. 
0 point:  2 students. 
Unfair, not evaluated:  2 solutions. 
